-
Posts
658 -
Joined
-
Last visited
-
Days Won
1
Content Type
Profiles
Forums
Blogs
Events
Blatmaps
Speed Championship Results
News
Website Help
Downloads
Gallery
Store
Posts posted by Purplemeanie
-
-
Looks to me as though the data portion of Mark's packet capture is set out something like how this document sets things out...
https://www.sbdmotorsport.co.uk/index.php/instructionpdf/index/186
The first byte of Mark's candump data output corresponds to the Identifier field in that PDF (01, 02, 03, 04 look the most interesting but there's clearly something also in the FF messages - which might be an end of stream message as mentioned earlier in this thread, but might also just be a NULL message dumped out at regular intervals if there's nothing else to transmit in that time slice).
So as an example from Mark's data,
#014F00003D009C46
might break down as:
01: Identifier 01
Which implies that:
4F: Engine Speed MSB
00 : Engine Speed LSB
etc
I guess the SBD PDF isn't actually the mappings used in the Caterham ECUs... but...
From what I can tell it looks as though that's all defined in Easimap under the System -> CAN Bus data stream menu and should be reasonably trivial to take the output from candump and parse it using the mappings from Easimap. Or have I got that all wrong?
John
-
Mark,
it looks to me as though the dump you've provided is:
29 bit ID: 0CBB0001
64 bit data: #FF00000000000000
Is that the way you're reading this? In which case the ID would stay the same if there's only one device transmitting on the bus??
John
-
Mark,
before you bought the Korlan CAN-USB widget, did you try the SBD interface with the SocketCAN drivers for Linux? Just wondering if I need to buy the Korlan interface or whether I can hook up the SBD interface to a Pi.
I presume you're using Linux to be able to use candump, right?
Also, to get an EasyMap pcap, are you going to use the SBD interface and the Korlan interface connected on a OBD y-cable? Or have you got some other cunning plan? I presume Wireshark won't capture the SBD interface packets on Windows... or will it?
John
-
In case anyone's interested, I've uploaded a video of my rear pad slapping in the caliper here:
(Note: this is an unlisted video, so you won't be able to search for it on YouTube, you'll need to use the link above)
John
-
I already have the hoses for the SV from Redline... just need the time :-)
-
I chased a rattle/knock from the rear end of my car for a while, tried all the things you mentioned. Turned out to be the rear brake pads rattling in the calipers. I could move the pads up and down in calipers by just moving them with my fingers poked through the spokes of the wheel.
They bounce up and down going over a bump giving a clanking noise.
Still haven't got round to fixing it because I want to switch out my copper brake lines to be flexible hoses and that project hasn't got to the top of my list yet. I'm expecting to find the spring clips are not installed correctly but others may have better suggestion.
Most passengers didn't notice it until I told them about it, and then they would hear it too. So not particularly obvious.
Just a thought.
John
-
Glad to hear I'm not imagining things Chris! :-)
Some of the confusion about where the submarine goes might be coming from how different people lay out their pipework. On my diagrams (and on the cars I'd seen to that point) the pipe from the back-right (offside) of the cylinder head is routed UNDER the back of the cylinder head to the submarine and then on to the bottom fitting on the heater control.
My diagrams are here in case anyone is interested: https://www.purplemeanie.co.uk/index.php/2017/09/23/build-session-17-5-caterham-420r-water-and-oil-overview/
Since then I've seen some people route that pipe from the back-right of the head up and over the back of the head, through the submarine and then to the bottom of the heater control. It makes it easier to adjust and tighten the jubilee clips on either side of the submarine but, IMHO, I think it makes the routing of the pipe to the heater less neat and doesn't give as much free space around the back of the battery for "other projects" I had in mind.
You pays your money and takes your choice :-)
I hope that hasn't confused things even further!
John
-
Hi Roger,
I'm not sure if this helps at all but while not getting my head around how the rear brake calipers work I pulled one apart and took a picture of the insides.
If that's not high enough res then I put a copy onto the blog post I mentioned above.
It might confuse you more than help, but I found I wanted to know how things worked before I would accept what others were telling me.
John
-
Hi Roger,
as p.mole1 says the pips being in the right place might be the issue. If I got this wrong though (I did once) the caliper wouldn’t fit over the pads, so perhaps not that.
As Jonathan says you have to make sure you do everything in the right order. If you apply the handbrake before filling and bleeding the brakes then you can get the self adjusters activated before they should be. This all confused the hell out of me when I recently built my 420 and I have half a blog post written about how the brakes and self adjusters work (sorry that doesn’t help a great deal for you though) - one day I may finish that off. You’ll need to rewind the pistons if that’s the case.
There might be something in the pictures on this page that help though...
John
-
Glad you're enjoying the blog Will. I must say you're doing well if you managed to read until the early hours, most people fall asleep (day or night) long before that! :-)
If you have any questions about the blog then please feel free to contact me, either on FB Messenger (JFPMartin) or email (john.martin@purplemeanie.co.uk). Or of course on this site.
John
-
Will,
I did like others for my build last year and bought CJ Autos smallest mobile axle stands. I bought the steel wheeled version but switched the castors out for “rubber” shod wheels that I bought from Amazon... made it much easier, and quieter, to wheel around my concrete garage.
I also had barked shins from the front cross member being too long but just cut it, and the rear, to be the right size for the application after a couple of hours of dancing around them.
Best purchase I made for the build. I still use them regularly to get the car up high to work on and to wheel it in and out of the garage when I’m working on it. In fact one of the best things about the mobile stands and a small garage was that I could get the build out onto my drive on a nice day and have extra space to work.
The height aspect was also worth the purchase for me. The CJ stands go high enough, and securely enough, to give plenty of room to work under the car. I also found myself leaning my head on the cross members as I lay under the car for long periods.
In terms of getting the engine hoist into place, you can see how I got on here...
Good luck with the build!
John
-
Totally agree with all comments - fantastic day on and off track. Made some great new friends and look forward to more club run track days.
John
-
Thanks Dave. Had a great day, everyone really friendly and great fun.
John
-
Thanks for the suggestion Geoff. I’ve got a busy holiday weekend to investigate all this. But great to have so many suggestions after I was thinking I’d got to the end of what could be wrong.
-
Thanks Ian. I'll check that out.
-
Thanks Jim. Some research needed into those points.
John
-
Hi Jim, thanks for the questions, it falls short by about an inch or so. If I lift it back up with my toe then it stays up. It probably falls short 50% of the time (but dependant on how hard I prod - a vigorous prod tends to bring the pedal all the way up) and about one in ten now it falls short enough not to turn off the brake lights (which I've adjusted the brake light switch as far as I dare).
Again, it doesn't fall short and is rock solid when the handbrake is partially applied. If I sit stationary in the car, apply handbrake and push the pedal - then the pedal remains high and solid even when the handbrake is disengaged. Only after some time and prodding does the pedal eventually drop.
Did that answer your question?
-
Good point Steve. But yes, bled inner's and outer's multiple times.
John
-
Elie boone, thanks,
I have the notches set correctly yes. I wouldn't have been able to get the pads into the calipers if the notches weren't upright.
I didn't test the MC disconnected from the pedal. That's a good suggestion though if my theory below doesn't work.
The bleed tool is off amazon. I don't think it's that. It provides plenty of pressure to push fluid through the lines and out of the bleed nipples. I've been reading up on some people who think pressurizing is not as good as vacuum - and I've bought a vacumm system just in case to try if all else fails. The theory being that a vacuum causes air bubble to become larger and exit where they're stuck, not sure that it will make that much of a difference but clutching at straws now. I don't think its that now though.
Current theory is that I didn't reset the LHS handbrake adjuster when I wound it in clockwise. I may try counter-clockwise and see if that works any better. Any advice on correct windback direction for RH and LH would be appreciated.
Update: hmmm.... having done a more specific search on here it seems that Clockwise is the right way to windback both LH and RH rear calipers. Still looking for suggestions.
-
Thanks for the reply Chris. I'm thinking it may be that I didn't reset the handbrake adjuster correctly on the LHS. There isn't much slack in around the clevis. I wasn't keen to just wind up the nut on threaded rod into the master cylinder.. that seemed a bit crass.
I think I'll have another go at resetting the handbrake auto adjusters when I get a chance.
Update: hmmm.... having done a more specific search on here it seems that Clockwise is the right way to windback both LH and RH rear calipers. Still looking for suggestions.
-
SM25T, thanks for the reply...
I already did the rear calipers. Handbrake slackened off completely. Wind pistons in. Pumped brake pedal - big and repeated pushes to reset. Only then re-adjusted handbrake.
Do I wind pistons clockwise on both sides? I saw a post saying to do clockwise on both sides but rewind kit comes with left and right versions.
Front calipers are fitted with bleed nipples at top - yes.
I'm pretty sure the pedal does not return still if MC cap is off. What's happening there if it does? I will try that this evening though.
Pedal return spring: Where is that fitted? Is it in the MC assembly or on the pedal assembly somewhere? The pedal returns fine to about 1 inch from the top of its travel - but I guess that's the pressure in the lines perhaps doing that.
Update: thinking about this. Can't see that it's anything to do with the MC and/or pedal. If the handbrake is on (slightly) then the pedal returns perfectly and with good feel. It's got to be something to do with the rear or else the handbrake would make no difference.
-
Hi All, I hope I can impose on your collective wisdom again and sorry for the long post...
I have a new build (by me) 420R with uprated 4 pot front brakes. The 420R also comes standard with the uprated master cylinder. I am through IVA and on the road but am finding the brake pedal feel is not as solid as I remember from test drives, and the pedal doesn't return to the top of it's travel. I have 160 miles on the clock... so open to the fact that this will get better... however...
I'm concerned that with the pedal not returning to the top of it's travel, after pressing the brakes, the brake lights will stay on. I've adjusted the brake-light switch as much as I dare so that the brakes only stay on occasionally now, but I'm worried that the brake lights will stay on and people following me don't appreciate that I'm braking again. I've had a couple of near misses already - or is this normal for people to rear-end a Caterham!
The brake pedal drops about half of its full travel with a solid push, and feels spongy (in non-assisted brake terms).
The tech at Williams reported that I probably had air in the system and bleeding them should get the pedal firmer and it should then return to the top position after pressing the pedal.
But... I've now bled the brakes 5 times. I've used the tried and tested: undo nipple, press pedal, close nipple, pedal up, repeat. I also bought a pressurized brake bleed system as used by the tech at Williams. Have used the pressurized system 4 times now.
The next piece of the puzzle is that the brake pedal feel is rock solid if the handbrake is slightly on.
So, having read various posts (though still not sure quite why) I have also slackened off the handbrake, taken the rear calipers off and wound back in the pistons. As part of this process I tipped and banged the calipers endlessly in the hope that any air pockets would be dislodged. I then fitted the calipers and pumped the brakes to set the pistons and reset the handbrake... no change.
My current theory is that for some reason the rear brake pads are coming too far off the discs when there's no pressure on the brake pedal... partially applying the handbrake will push the pads closer to the discs and pre-engage them for when the pedal is pressed - hence a firm pedal in that situation.
Any suggestions gratefully received. I have the club Novices Trackday booked for end of April and clearly keen to make sure I have great brakes by the time I get there.
Thanks in advance, John
-
Thanks for all the feedback. Wishbones now installed. Will do final checks when the car is on its own wheels.
-
Hi Jonathan,
As far as I can make out the upper Wishbones are identical OS vs NS. The ball joint orientation doesn’t seem to come into the equation.
At the moment ScottR440D’s statement is my default position unless anyone can tell us differently.
You asked where I am... Bristol.
John
ECU Diagnostics - CAN Bus, hunt for answers
in TechTalk
Posted
That makes things a little trickier then :-)
I guess that's why Mark was trying to parse the Easimap config files.
John